Modern consumers demand computer systems and processors that function at continually increasing frequencies. As processor frequencies increase, the frequency of the electromagnetic emissions increases, making it more difficult to shield electromagnetic radiation generated by these high frequency processors. Electromagnetic radiation can adversely effect circuit performance, and radiate from electronic equipment to threaten circuits in nearby equipment. There are also many regulatory requirements imposed on computer systems limiting the level of electromagnetic emissions that they produce.
One common method that has been used to shield electromagnetic radiation has been to use the chassis (or enclosure) to contain the electromagnetic energy within the chassis and block the energy from escaping. This is achieved by enclosing the electronics within a grounded conductive box. This requirement, however, makes it difficult to service the electronics and to cool the electronics, as any gaps in the conductive box allow electromagnetic radiation to escape.
To service the electronics there need to be removable panels and means to access the components in the interior of the unit. This creates cracks and seams that need to be sealed to block the electromagnetic radiation generated by the processors from escaping.
Also, to meet the cooling requirements of high-speed processors, a working fluid is moved through the chassis to remove the heat. The cheapest and simplest method is often to utilize air as the working fluid. The disadvantage of using air is that it has a relatively low thermal capacitance. Thus a large amount of air needs to be moved through the chassis to maintain proper temperatures. Vents are needed in the chassis to allow air into and out of the system. These vents allow some of the electromagnetic radiation to escape the enclosure. The size of the openings needs to be controlled to contain the energy within the enclosure. As the frequency increases the size of the openings needs to decrease to maintain containment. With the high frequency of the current processors, the allowable size of an opening in the box has gotten small enough that it is becoming difficult to design cost effective containment systems. Accordingly, it is believed that it is desirable to minimize the amount of electromagnetic radiation that needs to be contained by the enclosure.